General CMake cleanup/overhaul
* Enable precompiled headers for all projects
* Move specifications itto separate CMakeLists files
* Add openspace-core as a subdirectory
* Move handle_modules functionality into modules/CMakeLists.txt
* Move handleapplications logic into apps/CMakeLists.txt
* Introduce openspace-module-collection interface library to simplify inclusion of modules in applications
* Turn module initialization into a two-step process to adapt to the new minimal dependency scenario
* Compile time speedup
* Remove circular dependencies between modules and core preventing multithreaded compilation on MSVC
* Build Spice multithreaded and as static library
* Remove dependency from core to module-webbrowser
* Remove unused dependency from kameleon
* Remove additional unnecessary dependencies
* Cleanup volume/kameleon/kameleonvolume modules
* Fix visibility issues. Restrict include paths
* Compile kameleon in parallel
* Other cleanup
* Only copy CEF files from one target (hard-coded to OpenSpace right now)
* Remove unused instrumentation code
* Remove the ability to render AABB for globes as it caused a circular dependency between GlobeBrowsing and Debugging
* Removing compiler and cppcheck warnings
* Turn almost all includes into non-system includes
* Don't warn on deprecrated copy
* Updated submodules
* Cleanup
* CMake cleanups
* Update current year
* Update copyright header
* Use script to return list of all modules
* Update credits, license and ghoul
* Make height map fallback layer work again
* Add documentation to joystick button bindings
* Removed grouped property headers
* Add new version number constant generated by CMake
* Make Joystick deadzone work properly
* Change the startup date on Earth to today
* Fix key modifier handling
* Add debugging indices for TreeNodeDebugging
* Fix script schedule for OsirisRex
* Do not open Mission schedule automatically
* Upload default projection texture automatically
* General code cleanup
* Fix check_style_guide warnings
* Remove .clang-format
* MacOS compile fixes
* Clang analyzer fixes
* Rename OnScreenGui module to ImGui
* Support multiple external module folders (closes#31)
* Cleaning up CMake files
* Restructure application specification
* Add parameter for library mode to all modules
* Add functions to handle global variable state
* Misc/remove warnings (#383)
* Increase build timeout and do a clean rebuild every commit
